Lipo storage advice

[Mash Potato]

Probably been covered before but I did do a search and could not see the answer I was looking for.

Basically I'm not racing at the moment for one reason or another and have not used my B44 for ages as I have no batteries for it. I'd like to get some Lipo's for it to occasionally mess around with it, but obviously they would not be used often.
I've got a Bantam BC6 charger that has a storage mode. But basically what I want to know is if I get a Lipo or two and have them sat after setting to storage mode will this do the batts any harm? How long can they be stored in like this?